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Mukhtarov Nuriddin Shamsiddinovich, Institute of general and inorganic chemistry Academy of Sciences of Uzbekistan, doctor of philosophy E-mail: muknur@list.ru
DEVELOPMENT OF INNOVATIVE TECHNOLOGIES FOR THE PRODUCTION OF FUELS AND OILS WITH IMPROVED PERFORMANCE PROPERTIES
Abstract: According to existing ideas, depressant ability of the polymer depends on its compositional heterogeneity. The depressors polymethacrylate type of compositional heterogeneity is largely determined by the molecular weight distribution of alkyl groups in macromolecules of polymers or copolymers, and not for the macromolecules.
Keywords: polyalkylmethacrylate, polyalkylacrylate, polyvinylalkyl esters, pour point depressant properties, diesel fuel, lubricant, additive, axial oil, dispersion systems, disperser.
Currently in the global economic crisis, rational use of secondary resources and the new synthesized materials with the purpose of producing petroleum - diesel fuels and lubricants with improved performance and solving problems of import substitution determines the effectiveness of the developed new innovative technologies. Of particular importance is played by the implementation of target projects of modernization and technical updating of basic branches of economy, introduction of modern innovative technologies designed to give powerful impetus for the exit of Uzbekistan to a new level that ensures the competitiveness of our country on the world market [1].
The production of winter diesel fuel and lubricating oils implies the conformity of fuels and oils the requirements of the relevant standards for such low-temperature properties and as cloud point, pour point, cold filter plugging and sedimentation stability in storage conditions at temperatures below the cloud point. The best means of improving low-temperature properties of diesel fuels and oils, is the use of depressant-dispersant additives, and in the preparation oflubricating oils with a special role is played by the compositions of base oils.
Among the many depressants widespread co-polymers of ethylene with vinyl acetate, obtained at high pressures (up to 100 MPa and higher) and temperatures (100-150°C). Alkylmethacrylate copolymers of polar monomers are of interest due to a softer process conditions (the atmospheric pressure). But they do not show effectiveness in the primary low temperature indicator the temperature limit of filterability.
It should be particularly noted that depressants only inhibit the adhesion of paraffin crystals with the formation of sedentary patterns and may not prevent onset of crystallization. Therefore, the fuel with these additives during long-term storage is divided into two layers: the lower one enriched with paraffin crystals, and the upper light. Both layers retain mobility, but differ in the composition, and therefore the thermophysical characteristics. This disadvantage is eliminated by introducing into the fuel along with the depressor of another additive, called a dispersant paraffin's [2].
The most effective interaction between the depressor and n-alkane occurs when the depressor is released from the solution simultaneously with n-alkanol in the range of temperatures between the cloud point and
pour point, i.e. after the appearance of crystals of n-alkane, but before the formation of their spatial frame. Then closer together the temperatures of the separation of crystals of n-alkane and the depressor, the more effectively the depressor lowers the temperature limit of filterability, because it limits the size of crystals in the initial stage oftheir growth. Therefore, the copolymer released from solution in the fuel simultaneously with the crystals of n-alkanes gives a good depression ofthe freezing temperature, and the temperature limit of filterability. If the polymer is released from diesel fuel much higher temperature cloud point, it does not interact with the paraffin crystals formed and therefore has little effect on the pour point [3].
Maximum efficiency is achieved when the maximum depressor under the molecular weight distribution of the alkyl groups of the molecular weight distribution of n-alkanes of diesel fuel [4].
The presence of these two trends defines the character of the dependence of temperatures of glass transition and crystallization of comb-like polymers, the length of the side chain. This dependence is shown in figure, where the left branches of the curves indicate changes of the temperature of glass transition, and right - of melting. With increasing number of carbon atoms in the side branches increases the free volume of the system (increasing the porosity of the packing), and thus, decreases the glass transition temperature. In the field of values of n from 3 to 4 up to 9-10 amorphous polymers. Starting from n 9 to 12 a phase transition occurs from amorphous to crystalline polymers, and as n increases the melting point increases. Hypothetical limit of the melting point as n tends to infinity must be the melting point of polymethylene (polyethylene), exceeding 100 °C.
Figure. The dependence of the glass transition temperatures (light dots) and melting point (dark dots) of the length of the side chains in a series of comb-like polymers: 1 - polyalkylmethacrylate; 2 - polyalkylacrylate; 3 - simple polyvinylalkyl esters
Thus, the maximum solubility in hydrocarbons have polymethacrylates with long alkyl radicals from 8 to 12, because they, first, have a high affinity to hydrocarbons, and, secondly, have a minimum value of temperatures of glass transition and crystallization, which lies far below the working diapasons work depressants for diesel fuels. In order to reduce the solubility of polymethacrylate in hydrocarbons and increase the temperature of its crystallization,
to a temperature range of operation of the depressor can be used two ways. On the one hand, this can be achieved by reducing the thermodynamic affinity of the polymer to hydrocarbon, namely, the introduction into the copolymer of (meth)acrylates with shorter radicals, from 1 to 4 or more of other polar monomers, for example vinyl acetate, male inmate with substituents from 1 to 4, nitrogen-containing monomers or their derivatives quaternion, styrene,
methacrylate's of glycols and other. On the other hand, to increase the temperature of crystallization can be due to the weighting of the fractional composition of the basic monomers of methacrylate used in the synthesis of the copolymer. To do this, as the basic monomers can be used methacrylate's with long alkyl radicals from 16 to 24. At the same time using both, you can ensure that the composition of the alkyl radicals of polymethacrylate match the composition of the normal paraffin's of the fuel, and the temperature of its crystallization from the fuel corresponded to the temperature of crystallization of paraffin's.
As noted above, the base monomers in the synthesis of polymethacrylate depressants for oils and fuels are alkylmethacrylamide obtained on the basis of higher fatty alcohols, typically from C12 to C24. These monomers provide the basic characteristics of the depressor: solubility in hydrocarbons, and affinity for paraffins. To enhance the individual properties of depressants or giving them additional features (upon receipt of polyfunctional additives) in the composition of the injected polymer different comonomer usually functional. In organic synthesis industry fatty alcohols are produced, usually in the form of individual compounds and of fractions of definite composition. Used a number of fractions of fatty alcohols company SASOL brands NAFOL based on them were obtained three basic alkylmethacrylamide: MA NAFOL 1218K, MA NAFOL 1618S, MA NAFOL 2022. Investigated the effect of composition of copolymers on the basis of alkylmethacrylamide their depressant properties enabled us to carry out a scientific and methodical approach to solving problems of synthesis of alkylmethacrylamide, synthesis of dialkylitaconate alcohol NAFOL 1618S the synthesis ofpolyalkyl-methacrylates based on the MA NAFOL 1218K and analysis of the comparative characteristics of the obtained samples depressants which implies the following: polimethacrylates, obtained on the basis ofMA NAFOL 1218K has a high pour point depressant properties by lowering the pour point
when used in lubricating oils, especially when you get a new grease composition for lubrication of axle boxes of wheel pairs of locomotives, where it was possible to reduce pour points from -27 to -41°C with the development of technology for obtaining axle oil OM-Uz both summer and winter version. The introduction it in diesel fuel in amounts of 01 wt. % practically did not affect the cloud point. Depression of pour point at minus 13 °C.
When developing a dispersant for paraffin were used available raw materials, the use of which it is possible to conduct the synthesis in the soft mode, on an industrial scale. Compounds used in the quality of paraffin dispersants, exhibit surface activity in the system n-alkane-diesel fuel and help to stabilize the dispersion of n-alkanes in diesel fuel. These compounds should have a way to the surface of the n-alkanes, easily adsorbed on the surface of crystals of n-alkane depressor (or crystallization with them) and contain a polar or easily polarizable functional group capable of forming an electric double layer at the interfacial surface, thus leading to further stabilization of the dispersed system.
On the basis of the conducted production tests of the implementation, the use of a new dispersant paraffin's allowed to reduce the content of the pour point depressant additives in the package to 25 % compared with the additive package, consisting of a depressor Keroflux 6180 and dispersant paraffin's Keroflux 3614, currently used on Bukhara refinery.
When using 0.7% of the synthesized copolymers based alkylmethacrylates with other monomers in a mixture of dewaxed oil of the second fraction with dewaxed residual oil in the ratio of 2.8 has allowed to reduce the freezing point of the axial oil OM-Uz to - 27°C sample and when using as base oil a mixture of dewaxed oil selective and hydro treating with dewaxed residual oil in a ratio equal to 3 was able to reduce the freezing point to -41°C at 0.5% depressant in the total mixture.
As evidenced by the comparative physical and chemical properties, obtained lubricant comply with
the GOST 610-72 by the pour point to summer (sample No. 1) and winter options with improved performance characteristics according to the diameter of the spot of wear. Filed Patent application of the Republic of Uzbekistan № IAP 20140336, №. IAP 20160022 and developed innovative technologies of their production.
The new composition of the axial oil OM-Uz with depressant additive based on copolymers of al-kylmethacrylate successfully passed bench tests and operational tests at the consumer ofJSC "Uzbekis-ton Temir Yollari". The pilot batch in the amount of 58 tons is obtained. After a large-scale trials in the depot "Tinchlik" It will decide on the implementation and replication.
References:
1. Karimov I. A. World financial-economic crisis, ways and measures on its overcoming in conditions of Uzbekistan. -T.: - 2009. - 48 p.
2. Danilov A. M. Domestic additives for diesel fuels // World of petroleum products, - 2010. - P. 9-13.
3. Terteryan R. A. Depressant additives to oils, fuels, and oils. - M.: Chemistry. - 1990. - 240 p.
4. Grishina I. N., Lyubimenko V. A., Kolesnikov I. M., Vinokurov V. A. the Mechanism of action of depres-sor-dispersant additives to diesel fuels // proceedings of the VI International scientific-technical conference. Under the editorship of O. F. Glagoleva and E. A. Chernyshova. - M.: Technika, TUMAGROUP. - 2011. - P. 118-120.
